It's ONE per household per rebate offer/campaign and not for eternity and they occur pretty frequently; and I'm certain there are CREATIVE ways around such limitation. I've purchased CX500s at the Egg at a final cost as low as $9.99 ($39.99 list price minus $20 rebate minus $10 instant promo code discount). I have purchased several CX500s this way since the BFL Single SC days through the Cube era. I, in turn, had used the rebate VISA cards to purchase Egg gift cards and apply them to purchase more CX500s with ZERO out-of-pocket cost. That's the most bang for the buck for me.
If you use it for any length of time, the bronze will cost you more in the long run. Won't take long to recoup the $40-$50 you'd save having a gold 1300w PSU. Plus you need more outlets.
M
That's a fair assessment. It would be nice if you could illustrate the details of the figures though.
Off the top of my head, the difference between PSUs with 90% and 85% efficiency would be around 20WAC at the wall with a stock S3+ which equates to about 0.48kWh per day. At $0.12/kWh power rate, that's around $0.06/day difference. Therefore, $50 / $0.06 = 833 days = 28 months = 2.28 years to recoup a $50 difference in price. Is this what you had in mind?
Re needing more outlets, that's what power strips are for; and I've got enough of them already and I'm almost certain that most of us do. It could also be argued that using a single/dedicated PSU for each S3 eliminates a single point of failure of three S3s powered by a single PSU.
The CX500 is "at least 82%" according to NewEgg.
The Lightning 1300 is "at least 87%", and "up to 92%".
That 5% span is what you estimated above.
In typical manufacturer garble, the spec sheet lists the CX500 as "> 80%" and the Lightning as "> 87%". How that translates into "at least 82%" for the CX500 is anyone's guess.
Also remember you do get what you pay for. The golds are higher quality, will last longer, and will feed better power to your units. 2.28 years may seem like a long time, but I know I've had my PSUs around for mining longer than that. And if the day comes when I'm no longer mining, I'll likely find a new home easier for my gold PSU than your bronze PSU.
M
I just didn't pull random numbers out of a top hat. In fact, you didn't exactly provide supporting data with your "Won't take long to recoup the $40-$50 you'd save having a gold 1300w PSU" statement so I took the liberty of providing one in a jiffy. You made a statement without offering details to support such a statement; I merely tried to make sense out of it. Having said that, I don't go by what the Egg says or what Wikipedia says or what the spec sheet says in this case because there are more accurate PSU data in the form of actual 80 Plus certification test results. That's the whole point of the 80 Plus ratings, isn't it? The following links are actual test data of a CX500 and a Lightning-1300. Take note of the "actual" efficiency values and tell me if 5% efficiency difference between a "Gold" and "Bronze" is far off as you alluded, especially at around 80% load where we usually operate our PSUs at. Use the efficiency values at 50% load and at 100% load to interpolate and determine efficiency values at a given load in between using ratios and proportions:
http://www.plugloadsolutions.com/psu_reports/CORSAIR_75-001667_ECOS%203258_500W_Report.pdf
http://www.plugloadsolutions.com/psu_reports/ROSEWILL%20INC._LIGHTING-1300_ECOS%202330.1_1300W_Report.pdf
If you were gonna nitpick to squeeze out another 1% efficiency difference between them, then by all means, lets make it a 6% difference instead of 5%. That adds 0.1kWh/day -- from 0.5kWh/day to 0.6kWh/day. Again, based on $0.12/kWh, that's an increase from $0.06/day to $0.07/day; recouping a $50 price difference from 28 months to 24 months . Big deal!
When you admonished others in here about unnecessarily wasting money on expensive PSUs and suggested a cheaper alternative PSU (Rosewill Lightning-1300), I actually agreed with you:
https://bitcointalksearch.org/topic/m.8825455
However, it is funny that when I suggested a much cheaper alternative PSU (Corsair CX500) over your suggestion, you don't seem to agree with it which actually contradicts with your original point of saving money as far as PSU purchase is concerned.
I agree. You get what you pay for. I have a couple of XP boxes. I built them almost 15 years ago using a made-in-Taiwan-special generic PSU that I got from Fry's really dirt cheap. I still fire 'em up on a regular basis. I guess that counts as "getting what I paid for". Of course, I also have an assortment of PSUs including workhorses such as AX1200, AX850, GS600, CX500 (some have been mining continuously since the BFL days), some Antecs and more generic stuff. They are all still working...so, I guess I got what I paid for. In the end, it's all relative.
